It is of course well known to energize the electromagnetic control windings or coils of DC relays or contactors from an AC supply source through a full wave rectifier bridge. Due to the stored energy in a coil and the presence of the rectifier bridge, such relays or contactors are slow to release when the AC supply is interrupted. As a result the action of the armature or solenoid return springs are commensurately retarded. Thus the normal accelerating forces provided by such springs are damped resulting in slow opening of the relay or contactor contacts. As a consequence arc imparted burning and erosion of such contacts occurs limiting their useful life.
The Halbeck et al U.S. Pat. No. 3,594,614 assigned to the assignee of the present application discloses one expedient that has been devised to overcome such slow to release action of DC relays or contactors fed from an AC supply source through a full wave rectifier bridge. While generally satisfactory that expedient requires the use of an additional auxiliary DC relay which adds cost and weight.
It is a primary object of the present invention to provide an improved circuit for energizing and deenergizing the DC control winding of a relay or contactor from a source of AC supply which eliminates the need for auxiliary relays and the like.
A further object is to provide a circuit of the aforementioned type which employs solid state devices to control the energization and deenergization of such relays or contactors in a manner insuring comparatively rapid deenergization upon interruption of the AC supply to the rectifier bridge.
Other objects and advantages of the invention will hereinafter appear.